Primary Retinal Detachment

154
search for compounds with heparin-like qualities on growth factors,
but without the potential hemorrhagic issues. It is known that
fractionation of longer chains of heparin into smaller molecular
weight fragments causes loss of some of the anticoagulant activity
while preserving the ECM effects.As a result, low-molecular-weight
fractions of heparin with a molecular weight of 5000 or less retain
their ability to catalyze the inhibition of Factor Xa, but lose their
ability to directly inhibit thrombin [49]. When low-molecularweight
heparin was introduced into the infusate during vitrectomy
in an animal model, fibrin formation was markedly reduced without
any coincident increase in intraocular hemorrhage [50]. Use of
5 IU/ml of low-molecular-weight heparin in the infusate during
creation of an experimental model of proliferative vitreoretinopathy
reduced the rate of traction detachment from 77% to 28% at
3 months [51]. These encouraging results led to the inclusion of lowmolecular-weight
heparin in the infusate, along with 5-FU, which
was studied in the prevention of PVR in humans [15, 42, 50, 51].
In another important PVR trial, when conventional heparin
(1 IU/ml) was combined with a steroid dexamethasone (5 mg/ml)
in the infusate, there was a slight increase in the retinal reattachment
rate compared with controls from 65% to 80% in addition to
a reduction in the rate of reproliferation from 26.5% to 16%.A mild
increase in the rate of hyphema and vitreous hemorrhage was
seen, although it was not judged to be clinically significant [33].
Summary
7 Pharmacological Approaches to Improve Surgical Outcomes
Pharmacological methods remain a promising potential adjunct to
the successful treatment of retinal detachment. In addition to conventional
strategies, including adequate pupillary dilatation, control
of inflammation by anti-inflammatory agents, and intraocular
pressure by ocular hypotensive agents, drugs may play a further
role by inhibiting other late complications. These include proliferation
and macular edema. Steroids, fluoropyrimidines, and he-